Polymers and Electromagnetic Radiation: Fundamentals and Practical Applications

This first book to cover the interaction of polymers with radiation from the entire electromagnetic spectrum adopts a multidisciplinary approach to bridge polymer chemistry and physics, photochemistry, photophysics and materials science. The text is equally unique in its scope, devoting equal amounts of attention to the three aspects of synthesis, characterization, and applications. The first part deals with the interaction of polymers with non–ionizing radiation in the frequency–range from sub–terahertz via infrared radiation to visible and ultraviolet light, while the second covers interaction with ionizing radiation from the extreme ultraviolet to ?–ray photons. The result is a systematic overview of how both types of radiation can be used for different polymerization approaches, spectroscopy methods and lithography techniques. Authored by a world–renowned researcher and teacher with over 40 years of experience in the field, this is a highly practical and authoritative guide.

Preface IX Introduction 1 Part I Non–Ionizing Radiation 5 1 Sub–Terahertz Radiation Including Radiofrequency (RF) and Microwave Radiation 7 1.1 Absorption 7 1.1.1 General Aspects 7 1.1.2 Dissipation of Energy 9 1.1.2.1 Frequency Dependence 9 1.1.2.2 Temperature Dependence 13 1.2 Applications in Polymer Chemistry 15 1.2.1 General Aspects 15 1.2.2 Thermal Effects 16 1.2.2.1 Polymer Synthesis 17 1.2.2.2 Polymer Processing 21 1.2.2.3 Modification of Polymers 22 1.2.2.4 Polymer Degradation 22 1.2.2.5 Polymer Supports for Solid–Phase Organic Synthesis (SPOS) 23 1.2.3 Non–Thermal Effects 25 1.2.3.1 Unresolved Questions 25 1.2.3.2 Plasma–Assisted Chemistry 26 1.3 Applications in Polymer Physics 38 1.3.1 Dielectric Spectroscopy of Polymers 38 1.3.2 Microwave Probing of Electrical Conductivity in Polymers 40 1.3.3 Nondestructive Microwave Testing of Polymer Materials 43 1.4 Industrial Applications 46 References 49 2 Infrared Radiation 55 2.1 Absorption 55 2.1.1 General Aspects 55 2.1.2 Crystalline Polymers 61 2.1.3 Polarized IR Radiation 61 2.1.4 Far–IR Radiation 62 2.2 Applications 65 2.2.1 General Aspects 65 2.2.2 Mid–IR Analysis 67 2.2.2.1 Identification of Synthetic Polymers 67 2.2.2.2 Proteins 67 2.2.2.3 Nucleic Acids 69 2.2.3 NIR Analysis of Synthetic Organic Polymers 70 2.2.4 Far–IR Analysis of Polymers: Terahertz Spectroscopy 73 2.2.4.1 General Aspects 73 2.2.4.2 Nondestructive Testing of Plastic Articles: THz Imaging 76 2.2.4.3 THz Absorption by Biopolymers 77 2.2.4.4 THz Studies of Biopolymers in Liquid Water 77 2.2.4.5 Generation of THz Radiation in Poled Polymers 78 2.2.5 Special Applications 79 2.2.5.1 Thin Polymer Films 79 2.2.5.2 Orientation Measurements 85 2.2.5.3 IR Microspectroscopy and IR Imaging 90 2.3 Polymer Characterization by Two–Dimensional IR Spectroscopy 91 2.4 Time–Resolved Measurements in the mid–IR Range 93 2.4.1 In–Situ Monitoring of Chemical Reactions 93 2.4.2 Transient Two–Dimensional IR Spectroscopy 96 2.4.2.1 T–Jump Studies 96 2.4.2.2 Flash Photolysis 97 2.5 Time–Resolved THz Spectroscopy 98 2.5.1 Photoconductivity of Conjugated Polymers 98 2.5.2 Folding of Proteins 100 2.6 THz Optics Made From Polymers 101 References 102 3 Visible and Ultraviolet Light 109 3.1 Absorption 109 3.1.1 General Aspects 109 3.1.2 The Molecular Orbital Model 111 3.1.3 The Jablonski Diagram 113 3.1.4 Absorption in Synthetic Nonconjugated Polymers 114 3.1.5 Absorption in Synthetic Conjugated Polymers 115 3.1.6 Absorption in Biopolymers 118 3.1.7 Time–Resolved Spectroscopy 121 3.2 Applications 122 3.2.1 General Aspects 122 3.2.2 Applications in Polymer Chemistry 123 3.2.2.1 Polymer Synthesis 123 3.2.2.2 Modification of Synthetic Polymers 139 3.2.2.3 Modification of Biopolymers 158 3.2.3 Applications in Polymer Physics 164 3.2.3.1 Spectroscopy 164 3.2.3.2 Light Scattering 166 3.2.3.3 Raman Scattering 174 3.3 Technical Developments 176 3.3.1 Introductory Remarks 176 3.3.2 Photocuring 178 3.3.3 Photolithography 183 3.3.3.1 General Aspects 183 3.3.3.2 248 nm Lithography 187 3.3.3.3 193 nm Lithography 189 3.3.3.4 157 nm Lithography 190 3.3.4 Photovoltaics 192 3.3.5 Polymeric Light Sources 196 3.3.6 Holography 201 3.3.7 Xerography 204 3.3.8 Optical Waveguides 207 References 210 Part II Ionizing Radiation 225 4 Elementary Processes of the Interaction of High–Energy Photons with Matter 227 4.1 General Aspects 227 4.2 Attenuation Coefficients 228 4.3 Photoelectric Effect 230 4.4 Compton Scattering 234 4.5 Electron–Positron Pair Production 235 4.6 Photonuclear Absorption 235 4.7 Absorption of Swift Electrons 235 References 237 5 Chemical Reactions Induced by High–Energy Radiation 239 5.1 General Aspects 239 5.1.1 Radiation Sources and Electron Accelerators 242 5.2 Polymer Synthesis 243 5.2.1 Free–Radical Polymerization 243 5.2.2 Ionic Polymerization 247 5.2.3 Graft Copolymerization 251 5.2.4 Polymerization in the Solid State 253 5.3 Radiolysis of Bulk Synthetic Polymers 257 5.3.1 General Aspects 257 5.3.2 Product Formation in the Absence of Molecular Oxygen 258 5.3.3 Product Formation in the Presence of Molecular Oxygen 265 5.3.4 Radiation Stability and Protection 265 5.4 Radiolysis of Bulk Biopolymers 268 5.4.1 General Aspects 268 5.4.2 Nucleic Acids 268 5.4.3 Polysaccharides 270 5.4.4 Proteins 274 5.5 Radiolysis of Polymers in Solution 275 5.6 Technical Developments 285 5.6.1 General Aspects 285 5.6.2 Lithography 287 5.6.2.1 Introduction 287 5.6.2.2 Technical Performance 288 5.6.2.3 Resists 292 5.6.3 Crosslinking 303 5.6.4 Curing 304 5.6.5 Grafting 304 5.6.6 Hydrogels 306 References 307 6 Applications of High–Energy Radiation in Polymer Physics 315 6.1 General Aspects 315 6.2 X–Ray Spectroscopy 316 6.2.1 General Aspects 316 6.2.2 Near–Edge X–Ray Absorption Fine Structure (NEXAFS) Spectroscopy 317 6.2.3 Extended X–Ray Absorption Fine Structure (EXAFS) Spectroscopy 318 6.2.4 X–Ray Photoelectron Spectroscopy (XPS) 318 6.3 X–Ray Imaging and Microscopy 321 6.4 X–Ray Scattering 322 6.4.1 General Aspects 322 6.4.2 Crystalline Polymers 322 6.4.3 Polymer Solutions 330 References 335 Index 339

Wolfram Schnabel, born in Freiburg, Silesia, Germany, in 1931, is Professor Emeritus at the Technical University of Berlin. He obtained his PhD in Chemistry from Cologne University, Germany, and did post–doctoral research at Northwestern University, Evanston, USA. Subsequently he worked on his habilitation at the Technical University of Berlin and, in parallel, was researcher at the Hahn–Meitner–Institute Berlin, now merged in the Helmholtz Center Berlin for Materials and Energy. Wolfram Schnabel was appointed Professor at the Technical University of Berlin in 1974 and had this position until his retirement. He published well over 300 journal articles in the fields of macromolecular chemistry, photochemistry and radiation chemistry and is the author of three books.